Process and optimum pH for permeability enhancement of fractured granite through selective mineral dissolution by chelating agent flooding

•Permeability enhancement occurs via selective mineral dissolution in fractured granite.•Experimental analysis of the permeability enhancement process was performed.•The optimum pH for the permeability enhancement process was determined.•Successive use of first pH 4 and then pH 8 was optimum for enhancing permeability.•Two-fold or higher permeability enhancement was achieved in 4 h at the optimum pH.